Testing PWM output

Due to some problems with batteries, right we are unable to power our motors and escs, but we are trying to test and analyze the pwm outputs. So we armed the drone and used the controller to put high throttle.Then we went to see the servo output in the mission planner and this was the result:

I imagine that being in the ground without power on the motors and escs might provide results different from reality, but this is strange right?They all go to the same throttle value when you first put high throttle then, they start dropping.

Can someone explain what is happening? Is there other check or test that I could do?

Do not check it like that. You can not test a closed-loop control system in an open-loop.
Control theory 101.

ok the, without having the means of powering the motor and escs, what test can I do to check if the pwm that should be arriving if they were powered on is correct?

No test can do that.

ok, then we will just have to fix our battery situation, try to fly, and see the logs for confirm

Use Motor Test. Set the Throttle percentage to whatever you want and the duration long enough so you can switch to the Servo Output Screen to see the result. Then select one of the Test buttons.

I don’t see much point in this test.

Sorry my ignorance, the drone was showing some strange behavior when we did manage to fly it, we armed and we slowly raised the throttle and it was tilting.(We were doing slowly because if we went straight to high throttle he would go sideways). Now we are thinking if somehow the motors are receiving different pwm than they are supposed to and this is causing the tilt and we wanted to check.

This is more typically a Motor Order/direction problem. Connect the battery and use Motor Test to check this.

i have seen the motor drift a few weeks ago are you running Dshot? A new firmware build is addressing some issues but i not tested it. what firmware are you using and are you using Dshot mode?